Patent GB-1198836-A (GB)
Title: Diesel Engine Performance Analyzer
IPC: G01M15/09
Filed: 1967-09-26
Abstract: 1,198,836. Cathode-ray tube displays. MOBIL OIL CORP. 26 Sept., 1967, No. 43788/67. Heading H4T. [Also in Division F1] The pressure variations in the fuel injection lines of a diesel engine are investigated using a C.R.O. which is provided with reference and synchronizing pulses from a signal generator actuated by a motor driven by the output from one of the transducers, sensing the pressure variations, at the speed of the engine. The outputs of quartz crystal pressure transducers 10-12, Fig. 1, in the fuel injection lines of the engine are supplied via amplifiers 13-15 and 16 to the y input of a C.R.O. 17, the output from one transducer 10 being also used to energize the motor. Either the signal may be fed via pulse shaping circuits 18-35 which provide two square-wave signals of constant amplitude whose frequencies are equal to the repetition frequency of the input signal and which are displaced in phase by 90 degrees, to two inputs of a three-phase motor 31, whose third input is earthed, or the signal may be converted into a D.C. signal, Fig. 6 (not shown), whose amplitude is proportional to the repetition frequency of the input signal, and used to energize a D.C. motor (68). In each embodiment the motor is coupled to a transparent disc 38, Fig. 2 (not shown), provided with marks arranged in five concentric rings with 1, 2, 4, 6 and 8 marks in out ring. Pivotally attached to the centre of the disc are two relatively movable brackets 44, 45 provided with photo-sensitive diodes 501-509 corresponding to each ring of marks, which each, when a mark is interposed between it and light sources (49), (50), Fig. 5 (not shown), produces a pulse. Diode 505, producing one pulse per revolution, is connected via Schmitt trigger circuit 59 and amplifier 60 to the Y synch. of the C.R.O., the other diodes are connected to two four-way switches 57, 56 so that the number of pulses per revolution of the output from the switches is equal to the number of cylinders of the engine under investigation. Switch 56 is connected via Schmitt trigger circuit 57 and amplifier 58 to the X synch. of the C.R.O. while switch 51 is similarly connected to a stroboscope used to illuminate the top dead centre line on the engine flywheel and via switch 55 to the amplifier 16 to provide a reference trace on the C.R.O. In use, the bracket 45 is rotated relative to the disc so that the pulse produced by the transducer connected with the first cylinder of the engine appears on the first line of the oscilloscope. The bracket 44 is rotated so that the top dead centre line on the flywheel, illuminated by the stroboscope, appears to coincide with a fixed mark on the engine block so that the position of the reference pulse indicates the crank-shaft position on the oscilloscope. The angle between the two brackets, measured by a pointer and scale 46, 47, then indicates the position of the start of the injection on the crank wheel relative to the top dead centre line. The two brackets may be fixed in relative position by a locking nut 48 and rotated together with changing speed of the injection pump.